This invention relates to a method of preparing 4,4'-diphenoxybenzophenone.
4,4'-Diphenoxybenzophenone (DPBP) is useful inter alia as a monomer in the preparation of poly(arylene ether ketones) by Friedel-Crafts polymerization. See, e.g., the disclosures of Dahl et al., in U.S. Pat. No. 3,956,240; Rose, in U.S. Pat. No. 4,396,755 and U.S. Pat. No. 4,398,020; and Jansons et al., in U.S. Pat. No. 4,709,007.
Keller, in U.S. Pat. No. 3,366,691, proposed to make DPBP from diphenyl ether and phosgene. However, phosgene is a hazardous material requiring special equipment and handling procedures, making it undesirable as a starting material. Thus, it would be desirable to be able to synthesize DPBP without using phosgene.
We have invented a method of preparing DPBP with carbon dioxide as a starting material.